5 ms·

I have already witnessed false-positives with much more elaborate Covid tests so I would be surprised if this test is actually realiable.

Gys 6y ago
Did you read the text before making this comment? > They found that the new test had 96% sensitivity and 98% specificity.
- blueflow 6y ago
  I'm not sure if thats too good - 98% specificity means that for 1000 infected people, 20 will get away unidentified (false negative). But probably better than other tests, i guess?
  - libertine 6y ago
    But I guess that's why, in some countries, people who had a high probability of catching the virus are told to stay in quarantine even if they tested negative.
  - Gys 6y ago
    The text states this is comparable to PCR tests (molecular tests). So it is really not bad.
- tyho 6y ago
  In the UK, only 2.7% of tests are returning positive results. At the end of July, this figure was 0.4%, which puts a floor on the specificity of the existing testing technology at 99.6%. If a test with only 98% specificity were used in the UK, the test would have a positive predictive value (the chance that the positive test represents a true positive result) of about 50%, far worse than existing technology.
  - makomk 6y ago
    Yeah, that's the fundamental problem with this kind of cheap, quick test - it's really hard to get good enough specificity to make them viable. This is part of the reason the UK has rejected pretty much every such test it's tried, with Matt Hancock infamously declaring that "no test is better than a bad test" (though I think those tests were rather worse than this one).
  - LandR 6y ago
    WHere are you getting 2.7% from. In the last 24 hours in Scotland 12.8% of people tested were positive. It's been above 10%, I think, now for over two weeks.
    - iso1631 6y ago
      UK wise there's about 10,000 positive cases a day from 250,000 PCR tests E.g. 01-10-2020: 255,915 PCR tests processed, 11,988 cases dated then Obviously the testing cockup hasn't helped, but we're still on the order of 4% of tests coming back positive Scotland specifically hasn't had the cockup, Oct 1st was 762 cases (668 reported) from 14,316 cases, or about 5%.
      - LandR 6y ago
        See here: https://www.gov.scot/publications/coronavirus-covid-19-daily-data-for-scotland/ https://www.gov.scot/publications/coronavirus-covid-19-daily... 697 new cases of COVID-19 reported; this is 12.8% of newly tested individuals. Are some people tested multiple times and not a their tests come back positive?
        iso1631 6y ago
        That's an odd thing to report "The number of people newly tested refers to the number of individuals in Scotland who have been tested for the first time for COVID-19 on the previous day. Note that each person is only counted once regardless of repeat tests. This means that where someone tests positive after receiving a negative test result on a previous day, they would be counted in the new positive cases for that day but in the number of people newly tested on the day they first received a test result." So if I were tested in August as I had a cough, and it came back negative, but now I have a temperature, and test positive, I wouldn't count as a newly tested person. The 697 new cases would include my number, but the 5445 newly tested people wouldn't. It's very possible for new cases to outnumber newly tested people, so dividing one number by another makes no sense at all. It's concerning that the Scotish government are linking these two numbers.
- deleted 6y ago
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Gys 6y ago

Did you read the text before making this comment? > They found that the new test had 96% sensitivity and 98% specificity.

blueflow 6y ago
I'm not sure if thats too good - 98% specificity means that for 1000 infected people, 20 will get away unidentified (false negative). But probably better than other tests, i guess?
- libertine 6y ago
  But I guess that's why, in some countries, people who had a high probability of catching the virus are told to stay in quarantine even if they tested negative.
- Gys 6y ago
  The text states this is comparable to PCR tests (molecular tests). So it is really not bad.
tyho 6y ago
In the UK, only 2.7% of tests are returning positive results. At the end of July, this figure was 0.4%, which puts a floor on the specificity of the existing testing technology at 99.6%. If a test with only 98% specificity were used in the UK, the test would have a positive predictive value (the chance that the positive test represents a true positive result) of about 50%, far worse than existing technology.
- makomk 6y ago
  Yeah, that's the fundamental problem with this kind of cheap, quick test - it's really hard to get good enough specificity to make them viable. This is part of the reason the UK has rejected pretty much every such test it's tried, with Matt Hancock infamously declaring that "no test is better than a bad test" (though I think those tests were rather worse than this one).
- LandR 6y ago
  WHere are you getting 2.7% from. In the last 24 hours in Scotland 12.8% of people tested were positive. It's been above 10%, I think, now for over two weeks.
  - iso1631 6y ago
    UK wise there's about 10,000 positive cases a day from 250,000 PCR tests E.g. 01-10-2020: 255,915 PCR tests processed, 11,988 cases dated then Obviously the testing cockup hasn't helped, but we're still on the order of 4% of tests coming back positive Scotland specifically hasn't had the cockup, Oct 1st was 762 cases (668 reported) from 14,316 cases, or about 5%.
    - LandR 6y ago
      See here: https://www.gov.scot/publications/coronavirus-covid-19-daily-data-for-scotland/ https://www.gov.scot/publications/coronavirus-covid-19-daily... 697 new cases of COVID-19 reported; this is 12.8% of newly tested individuals. Are some people tested multiple times and not a their tests come back positive?
      - iso1631 6y ago
        That's an odd thing to report "The number of people newly tested refers to the number of individuals in Scotland who have been tested for the first time for COVID-19 on the previous day. Note that each person is only counted once regardless of repeat tests. This means that where someone tests positive after receiving a negative test result on a previous day, they would be counted in the new positive cases for that day but in the number of people newly tested on the day they first received a test result." So if I were tested in August as I had a cough, and it came back negative, but now I have a temperature, and test positive, I wouldn't count as a newly tested person. The 697 new cases would include my number, but the 5445 newly tested people wouldn't. It's very possible for new cases to outnumber newly tested people, so dividing one number by another makes no sense at all. It's concerning that the Scotish government are linking these two numbers.
deleted 6y ago
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